Copyright>        OpenRadioss
Copyright>        Copyright (C) 1986-2023 Altair Engineering Inc.
Copyright>
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Copyright>
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Copyright>        Commercial Alternative: Altair Radioss Software
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Copyright>        As an alternative to this open-source version, Altair also offers Altair Radioss
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Chd|====================================================================
Chd|  MODSTI                        source/time_step/modsti.F     
Chd|-- called by -----------
Chd|        RESOL                         source/engine/resol.F         
Chd|-- calls ---------------
Chd|====================================================================
      SUBROUTINE MODSTI(NODFT,NODLT,STIFN,VISCN,MS)
C-----------------------------------------------
C   I m p l i c i t   T y p e s
C-----------------------------------------------
#include      "implicit_f.inc"
C-----------------------------------------------
C   C o m m o n   B l o c k s
C-----------------------------------------------
C
      INTEGER NODFT,NODLT
      my_real 
     .  STIFN(*),VISCN(*),MS(*)
C----------------------------------------
C   L o c a l   V a r i a b l e s
C----------------------------------------
      INTEGER I,N
      my_real 
     .  C2,C21,AUX
C----------------------------------------
       DO I=NODFT,NODLT
        IF(MS(I)>ZERO)THEN
         C2      = FOUR*VISCN(I)*VISCN(I)
         C21     = EIGHT*MS(I)*STIFN(I)
         AUX     = SQRT(C2+C21)+2.*VISCN(I)
         STIFN(I)= ONE_OVER_8*AUX*AUX/MAX(MS(I),EM30)
C        STIFN(I)= STIFN(I)*AUX*AUX/MAX(C21,EM30)
         STIFN(I)= MAX(STIFN(I),TWO*VISCN(I)*VISCN(I)/MAX(MS(I),EM30))
         VISCN(I)= ZERO
        ENDIF
       ENDDO
C
      RETURN
      END
